Question

The half-life of third order reaction is given by which equation
​

Answer 1

Explanation:

Only 1st order equations have the exponential decay which leads to a natural time constant.

A 3rd order reaction has time dependence given by:

d[A]/dt = -k[A]^3

This integrates up to give: T = 1/( 2k[A]^2)¦ evaluated at the two times in question

You can see that the time to go to half concentration depends on the concentration, unlike the first order case where the time to half value is independent of the concentration.

If the 3rd order reaction has time dependence given by:

d[A]/dt = -k[A] * [B]^2

or d[A]/dt = -k[A][B][C]

And [B] and [C] are only marginally